Convolutional Neural Networks

Project: Write an Algorithm for a Dog Identification App


In this notebook, some template code has already been provided for you, and you will need to implement additional functionality to successfully complete this project. You will not need to modify the included code beyond what is requested. Sections that begin with '(IMPLEMENTATION)' in the header indicate that the following block of code will require additional functionality which you must provide. Instructions will be provided for each section, and the specifics of the implementation are marked in the code block with a 'TODO' statement. Please be sure to read the instructions carefully!

Note: Once you have completed all of the code implementations, you need to finalize your work by exporting the Jupyter Notebook as an HTML document. Before exporting the notebook to html, all of the code cells need to have been run so that reviewers can see the final implementation and output. You can then export the notebook by using the menu above and navigating to File -> Download as -> HTML (.html). Include the finished document along with this notebook as your submission.

In addition to implementing code, there will be questions that you must answer which relate to the project and your implementation. Each section where you will answer a question is preceded by a 'Question X' header. Carefully read each question and provide thorough answers in the following text boxes that begin with 'Answer:'. Your project submission will be evaluated based on your answers to each of the questions and the implementation you provide.

Note: Code and Markdown cells can be executed using the Shift + Enter keyboard shortcut. Markdown cells can be edited by double-clicking the cell to enter edit mode.

The rubric contains optional "Stand Out Suggestions" for enhancing the project beyond the minimum requirements. If you decide to pursue the "Stand Out Suggestions", you should include the code in this Jupyter notebook.


Why We're Here

In this notebook, you will make the first steps towards developing an algorithm that could be used as part of a mobile or web app. At the end of this project, your code will accept any user-supplied image as input. If a dog is detected in the image, it will provide an estimate of the dog's breed. If a human is detected, it will provide an estimate of the dog breed that is most resembling. The image below displays potential sample output of your finished project (... but we expect that each student's algorithm will behave differently!).

Sample Dog Output

In this real-world setting, you will need to piece together a series of models to perform different tasks; for instance, the algorithm that detects humans in an image will be different from the CNN that infers dog breed. There are many points of possible failure, and no perfect algorithm exists. Your imperfect solution will nonetheless create a fun user experience!

The Road Ahead

We break the notebook into separate steps. Feel free to use the links below to navigate the notebook.

  • Step 0: Import Datasets
  • Step 1: Detect Humans
  • Step 2: Detect Dogs
  • Step 3: Create a CNN to Classify Dog Breeds (from Scratch)
  • Step 4: Create a CNN to Classify Dog Breeds (using Transfer Learning)
  • Step 5: Write your Algorithm
  • Step 6: Test Your Algorithm

Step 0: Import Datasets

Make sure that you've downloaded the required human and dog datasets:

Note: if you are using the Udacity workspace, you DO NOT need to re-download these - they can be found in the /data folder as noted in the cell below.

  • Download the dog dataset. Unzip the folder and place it in this project's home directory, at the location /dog_images.

  • Download the human dataset. Unzip the folder and place it in the home directory, at location /lfw.

Note: If you are using a Windows machine, you are encouraged to use 7zip to extract the folder.

In the code cell below, we save the file paths for both the human (LFW) dataset and dog dataset in the numpy arrays human_files and dog_files.

In [1]:
import numpy as np
from glob import glob

# load filenames for human and dog images
human_files = np.array(glob("/data/lfw/*/*"))
dog_files = np.array(glob("/data/dog_images/*/*/*"))

# print number of images in each dataset
print('There are %d total human images.' % len(human_files))
print('There are %d total dog images.' % len(dog_files))
There are 13233 total human images.
There are 8351 total dog images.

Step 1: Detect Humans

In this section, we use OpenCV's implementation of Haar feature-based cascade classifiers to detect human faces in images.

OpenCV provides many pre-trained face detectors, stored as XML files on github. We have downloaded one of these detectors and stored it in the haarcascades directory. In the next code cell, we demonstrate how to use this detector to find human faces in a sample image.

In [2]:
import cv2                
import matplotlib.pyplot as plt                        
%matplotlib inline                               

# extract pre-trained face detector
face_cascade = cv2.CascadeClassifier('haarcascades/haarcascade_frontalface_alt.xml')

# load color (BGR) image
img = cv2.imread(human_files[0])
# convert BGR image to grayscale
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

# find faces in image
faces = face_cascade.detectMultiScale(gray)

# print number of faces detected in the image
print('Number of faces detected:', len(faces))

# get bounding box for each detected face
for (x,y,w,h) in faces:
    # add bounding box to color image
    cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
    
# convert BGR image to RGB for plotting
cv_rgb = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

# display the image, along with bounding box
plt.imshow(cv_rgb)
plt.show()
Number of faces detected: 1

Before using any of the face detectors, it is standard procedure to convert the images to grayscale. The detectMultiScale function executes the classifier stored in face_cascade and takes the grayscale image as a parameter.

In the above code, faces is a numpy array of detected faces, where each row corresponds to a detected face. Each detected face is a 1D array with four entries that specifies the bounding box of the detected face. The first two entries in the array (extracted in the above code as x and y) specify the horizontal and vertical positions of the top left corner of the bounding box. The last two entries in the array (extracted here as w and h) specify the width and height of the box.

Write a Human Face Detector

We can use this procedure to write a function that returns True if a human face is detected in an image and False otherwise. This function, aptly named face_detector, takes a string-valued file path to an image as input and appears in the code block below.

In [3]:
# returns "True" if face is detected in image stored at img_path
def face_detector(img_path):
    img = cv2.imread(img_path)
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    faces = face_cascade.detectMultiScale(gray)
    return len(faces) > 0

(IMPLEMENTATION) Assess the Human Face Detector

Question 1: Use the code cell below to test the performance of the face_detector function.

  • What percentage of the first 100 images in human_files have a detected human face?
  • What percentage of the first 100 images in dog_files have a detected human face?

Ideally, we would like 100% of human images with a detected face and 0% of dog images with a detected face. You will see that our algorithm falls short of this goal, but still gives acceptable performance. We extract the file paths for the first 100 images from each of the datasets and store them in the numpy arrays human_files_short and dog_files_short.

Answer: (You can print out your results and/or write your percentages in this cell)

In [4]:
from tqdm import tqdm

human_files_short = human_files[:100]
dog_files_short = dog_files[:100]

#-#-# Do NOT modify the code above this line. #-#-#

## TODO: Test the performance of the face_detector algorithm 
## on the images in human_files_short and dog_files_short.
humans = 0
dogs = 0
for idx, file in enumerate(tqdm(human_files_short)):
    
    humans += face_detector(file)
    
for idx, file in enumerate(tqdm(dog_files_short)):
    
    dogs += face_detector(file)
        

print('number of human faces detected:{}/100'.format(humans))
print('number of human faces detected in dog files:{}'.format(dogs))
100%|██████████| 100/100 [00:02<00:00, 35.23it/s]
100%|██████████| 100/100 [00:30<00:00,  3.33it/s]
number of human faces detected:98/100
number of human faces detected in dog files:17

In [5]:
#Accuracy in detecting human faces
print('accuracy in detecting human faces: {}%'.format(humans/len(human_files_short) *100))
accuracy in detecting human faces: 98.0%

We suggest the face detector from OpenCV as a potential way to detect human images in your algorithm, but you are free to explore other approaches, especially approaches that make use of deep learning :). Please use the code cell below to design and test your own face detection algorithm. If you decide to pursue this optional task, report performance on human_files_short and dog_files_short.


Step 2: Detect Dogs

In this section, we use a pre-trained model to detect dogs in images.

Obtain Pre-trained VGG-16 Model

The code cell below downloads the VGG-16 model, along with weights that have been trained on ImageNet, a very large, very popular dataset used for image classification and other vision tasks. ImageNet contains over 10 million URLs, each linking to an image containing an object from one of 1000 categories.

In [6]:
import torch
import torchvision.models as models

# define VGG16 model
VGG16 = models.vgg16(pretrained=True)

# check if CUDA is available
use_cuda = torch.cuda.is_available()

# move model to GPU if CUDA is available
if use_cuda:
    VGG16 = VGG16.cuda()

Given an image, this pre-trained VGG-16 model returns a prediction (derived from the 1000 possible categories in ImageNet) for the object that is contained in the image.

(IMPLEMENTATION) Making Predictions with a Pre-trained Model

In the next code cell, you will write a function that accepts a path to an image (such as 'dogImages/train/001.Affenpinscher/Affenpinscher_00001.jpg') as input and returns the index corresponding to the ImageNet class that is predicted by the pre-trained VGG-16 model. The output should always be an integer between 0 and 999, inclusive.

Before writing the function, make sure that you take the time to learn how to appropriately pre-process tensors for pre-trained models in the PyTorch documentation.

In [7]:
from PIL import Image
import torchvision.transforms as transforms

def VGG16_predict(img_path):
    '''
    Use pre-trained VGG-16 model to obtain index corresponding to 
    predicted ImageNet class for image at specified path
    
    Args:
        img_path: path to an image
        
    Returns:
        Index corresponding to VGG-16 model's prediction
    '''
    
    ## TODO: Complete the function.
    ## Load and pre-process an image from the given img_path
    ## Return the *index* of the predicted class for that image
    
    img = Image.open(img_path)
    transform_pipeline = transforms.Compose([transforms.Resize(size = (244, 244)),
                                             transforms.ToTensor()])
    
    img_tensor = transform_pipeline(img)
    img_tensor = img_tensor.unsqueeze(0) 
    
    # move tensor to cuda
    if torch.cuda.is_available():
        img_tensor = img_tensor.cuda()

    prediction = VGG16(img_tensor)
    
    # move tensor to cpu, for cpu processing
    if torch.cuda.is_available():
        prediction = prediction.cpu()

    index = prediction.data.numpy().argmax()
        
    return index

(IMPLEMENTATION) Write a Dog Detector

While looking at the dictionary, you will notice that the categories corresponding to dogs appear in an uninterrupted sequence and correspond to dictionary keys 151-268, inclusive, to include all categories from 'Chihuahua' to 'Mexican hairless'. Thus, in order to check to see if an image is predicted to contain a dog by the pre-trained VGG-16 model, we need only check if the pre-trained model predicts an index between 151 and 268 (inclusive).

Use these ideas to complete the dog_detector function below, which returns True if a dog is detected in an image (and False if not).

In [8]:
### returns "True" if a dog is detected in the image stored at img_path
def dog_detector(img_path):
    ## TODO: Complete the function.
    index = VGG16_predict(img_path)
    #print(index)
    
    return (151 <= index and index <= 268) # true/false

(IMPLEMENTATION) Assess the Dog Detector

Question 2: Use the code cell below to test the performance of your dog_detector function.

  • What percentage of the images in human_files_short have a detected dog?
  • What percentage of the images in dog_files_short have a detected dog?

Answer:

In [9]:
### TODO: Test the performance of the dog_detector function
### on the images in human_files_short and dog_files_short.

# tqdm is not necessary, due to it is quite fast

human_files_detected_as_human = np.average([dog_detector(img) for img in human_files_short])
dog_files_detected_as_human = np.average([dog_detector(img) for img in dog_files_short])

print('Avg Human is detected as Dog : {}%'.format(human_files_detected_as_human*100))
print('Avg Accuracy Dog : {}%'.format(dog_files_detected_as_human*100))
Avg Human is detected as Dog : 0.0%
Avg Accuracy Dog : 100.0%

We suggest VGG-16 as a potential network to detect dog images in your algorithm, but you are free to explore other pre-trained networks (such as Inception-v3, ResNet-50, etc). Please use the code cell below to test other pre-trained PyTorch models. If you decide to pursue this optional task, report performance on human_files_short and dog_files_short.


Step 3: Create a CNN to Classify Dog Breeds (from Scratch)

Now that we have functions for detecting humans and dogs in images, we need a way to predict breed from images. In this step, you will create a CNN that classifies dog breeds. You must create your CNN from scratch (so, you can't use transfer learning yet!), and you must attain a test accuracy of at least 10%. In Step 4 of this notebook, you will have the opportunity to use transfer learning to create a CNN that attains greatly improved accuracy.

We mention that the task of assigning breed to dogs from images is considered exceptionally challenging. To see why, consider that even a human would have trouble distinguishing between a Brittany and a Welsh Springer Spaniel.

Brittany Welsh Springer Spaniel

It is not difficult to find other dog breed pairs with minimal inter-class variation (for instance, Curly-Coated Retrievers and American Water Spaniels).

Curly-Coated Retriever American Water Spaniel

Likewise, recall that labradors come in yellow, chocolate, and black. Your vision-based algorithm will have to conquer this high intra-class variation to determine how to classify all of these different shades as the same breed.

Yellow Labrador Chocolate Labrador Black Labrador

We also mention that random chance presents an exceptionally low bar: setting aside the fact that the classes are slightly imabalanced, a random guess will provide a correct answer roughly 1 in 133 times, which corresponds to an accuracy of less than 1%.

Remember that the practice is far ahead of the theory in deep learning. Experiment with many different architectures, and trust your intuition. And, of course, have fun!

(IMPLEMENTATION) Specify Data Loaders for the Dog Dataset

Use the code cell below to write three separate data loaders for the training, validation, and test datasets of dog images (located at dog_images/train, dog_images/valid, and dog_images/test, respectively). You may find this documentation on custom datasets to be a useful resource. If you are interested in augmenting your training and/or validation data, check out the wide variety of transforms!

In [10]:
import os
os.listdir('/data/dog_images/')
from torchvision import datasets
from PIL import ImageFile
ImageFile.LOAD_TRUNCATED_IMAGES = True
In [11]:
# Samples per batch
batch_size = 20
# Subprocesses used
num_workers = 0

# Image transforms
transformations = {
    'train': transforms.Compose([transforms.RandomResizedCrop(224),
                                transforms.RandomHorizontalFlip(),
                                transforms.RandomRotation(5),
                                transforms.ToTensor(),
                                transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])]),
    'valid': transforms.Compose([transforms.Resize(size=(248)),
                                transforms.CenterCrop(224),
                                transforms.ToTensor(),
                                transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])]),
    'test': transforms.Compose([transforms.Resize(size=(224,224)),
                                transforms.ToTensor(),
                                transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])])
}
In [12]:
# Directories
train_dir = '/data/dog_images/train/'
validation_dir = '/data/dog_images/valid/'
test_dir = '/data/dog_images/test/'
In [13]:
# Data Loaders
train_data = datasets.ImageFolder(train_dir, transform=transformations['train'])
validation_data = datasets.ImageFolder(validation_dir, transform=transformations['valid'])
test_data = datasets.ImageFolder(test_dir, transform=transformations['test'])

train_loader = torch.utils.data.DataLoader(train_data,
                                           batch_size=batch_size, 
                                           num_workers=num_workers,
                                           shuffle=True)
validation_loader = torch.utils.data.DataLoader(validation_data,
                                           batch_size=batch_size, 
                                           num_workers=num_workers,
                                           shuffle=True)
test_loader = torch.utils.data.DataLoader(test_data,
                                           batch_size=batch_size, 
                                           num_workers=num_workers,
                                           shuffle=False)

loaders_scratch = {
    'train': train_loader,
    'valid': validation_loader,
    'test': test_loader
}

Question 3: Describe your chosen procedure for preprocessing the data.

  • How does your code resize the images (by cropping, stretching, etc)? What size did you pick for the input tensor, and why?
  • Did you decide to augment the dataset? If so, how (through translations, flips, rotations, etc)? If not, why not?

Answer:

Answer 1 :-

1 ) Images are resized to 224 for inputing into the VGG16 model.

2 ) Training Data use a random crop method.

3 ) Testing Data uses Center Crop method.

Answer 2:-

1 ) Yes, I have augument the data. It helps me to avoid overfittig the model. For Training Images, I have used Random Rotation, Random Horizontal Flip and Random Crop.

2 )All the images are Normalized.

Note :- I tried to create a model without using Augument but accuracy of model was less than 10 percent. More over Validation loss started increasing heavly after 5 epoches. So I changes my strategy.

(IMPLEMENTATION) Model Architecture

Create a CNN to classify dog breed. Use the template in the code cell below.

In [14]:
import torch.nn as nn
import torch.nn.functional as F

# define the CNN architecture
class Net(nn.Module):
    ### TODO: choose an architecture, and complete the class
    def __init__(self):
        super(Net, self).__init__()
        ## Define layers of a CNN
        # Convolutional layers
        self.conv1 = nn.Conv2d(3, 32, 3, padding=1)
        self.conv2 = nn.Conv2d(32, 64, 3, stride=2, padding=1)
        self.conv3 = nn.Conv2d(64, 128, 3, stride=2, padding=1)
        
        # Max pooling layer
        self.pool = nn.MaxPool2d(2, 2)
        
        # Dropout layer
        self.dropout = nn.Dropout(0.3)
        
        # Linear layer (For classification)
        # 133 dog classes are present
        self.fc1 = nn.Linear(128*7*7, 784)
        self.fc2 = nn.Linear(784, 133)
    
    def forward(self, x):
        ## Define forward behavior
        x = F.relu(self.conv1(x))
        x = self.pool(x)
        x = F.relu(self.conv2(x))
        x = self.pool(x)
        x = F.relu(self.conv3(x))
        x = self.pool(x)
        
        # Preparation for linear layer
        x = x.view(-1, 7*7*128)
        
        # Classification
        x = self.dropout(x)
        x = F.relu(self.fc1(x))
        x = self.dropout(x)
        x = self.fc2(x)
                
        return x

#-#-# You so NOT have to modify the code below this line. #-#-#

# instantiate the CNN
model_scratch = Net()

# move tensors to GPU if CUDA is available
if use_cuda:
    model_scratch.cuda()

Question 4: Outline the steps you took to get to your final CNN architecture and your reasoning at each step.

Answer:

1 ) There are three conv layers.

2 ) There is one max pooling layer between conv layers.

3 ) When image is passed conv layer, I've add one maxpool, to downsize featrue mape, and it also avoids overfitting for each conv layers.

4 ) As per passing conv layers, width/height are downsized like below.

(250,250) this is input image size.

-> (125,125)

-> (62,62)

-> (28,28)

5 ) And it is connected to last fully connected layer and its size is 133 as it is same with total classes of dog.

6 ) Dropout layer also used to avoid overfitting.

(IMPLEMENTATION) Specify Loss Function and Optimizer

Use the next code cell to specify a loss function and optimizer. Save the chosen loss function as criterion_scratch, and the optimizer as optimizer_scratch below.

In [15]:
import torch.optim as optim

### TODO: select loss function
criterion_scratch = nn.CrossEntropyLoss()

### TODO: select optimizer
optimizer_scratch = optim.SGD(model_scratch.parameters(), lr = 0.04)

(IMPLEMENTATION) Train and Validate the Model

Train and validate your model in the code cell below. Save the final model parameters at filepath 'model_scratch.pt'.

In [16]:
def train(n_epochs, loaders, model, optimizer, criterion, use_cuda, save_path):
    """returns trained model"""
    # initialize tracker for minimum validation loss
    valid_loss_min = np.Inf 
    
    for epoch in range(1, n_epochs+1):
        # initialize variables to monitor training and validation loss
        train_loss = 0.0
        valid_loss = 0.0
        
        ###################
        # train the model #
        ###################
        model.train()
        
        for batch_idx, (data, target) in enumerate(loaders['train']):
            # move to GPU
            if use_cuda:
                data, target = data.cuda(), target.cuda()
            ## find the loss and update the model parameters accordingly
            ## record the average training loss, using something like
            ## train_loss = train_loss + ((1 / (batch_idx + 1)) * (loss.data - train_loss))
            
            # clear the gradients of all optimized variables
            optimizer.zero_grad()
            
            # forward pass
            output = model(data)
            
            # calculating the loss
            loss = criterion(output, target)
            
            # backprop
            loss.backward()
            optimizer.step()
            
            
            # updating the training loss
            train_loss = train_loss + ((1 / (batch_idx + 1)) * (loss.data - train_loss))
        
        ######################    
        # validate the model #
        ######################
        model.eval()
        for batch_idx, (data, target) in enumerate(loaders['valid']):
            # move to GPU
            if use_cuda:
                data, target = data.cuda(), target.cuda()
            ## update the average validation loss
            
            # forward pass
            output = model(data)
            
            # calculating the  loss
            loss = criterion(output, target)
            
            # updating the average validation loss 
            valid_loss = valid_loss + ((1 / (batch_idx + 1)) * (loss.data - valid_loss))
            
        # print training/validation statistics 
        print('Epoch: {} \tTraining Loss: {:.6f} \tValidation Loss: {:.6f}'.format(
            epoch, 
            train_loss,
            valid_loss
            ))
        
        ## TODO: save the model if validation loss has decreased
        if valid_loss < valid_loss_min:
            torch.save(model.state_dict(), save_path)
            print('Validation loss decreased ({:.6f} --> {:.6f}).  Saving model ...'.format(
            valid_loss_min,
            valid_loss))
            valid_loss_min = valid_loss
        
    # return trained model
    return model

# train the model
model_scratch = train(25, loaders_scratch, model_scratch, optimizer_scratch, 
                      criterion_scratch, use_cuda, 'model_scratch.pt')

# load the model that got the best validation accuracy
model_scratch.load_state_dict(torch.load('model_scratch.pt'))
Epoch: 1 	Training Loss: 4.869244 	Validation Loss: 4.811542
Validation loss decreased (inf --> 4.811542).  Saving model ...
Epoch: 2 	Training Loss: 4.782327 	Validation Loss: 4.681364
Validation loss decreased (4.811542 --> 4.681364).  Saving model ...
Epoch: 3 	Training Loss: 4.647170 	Validation Loss: 4.465849
Validation loss decreased (4.681364 --> 4.465849).  Saving model ...
Epoch: 4 	Training Loss: 4.568083 	Validation Loss: 4.385202
Validation loss decreased (4.465849 --> 4.385202).  Saving model ...
Epoch: 5 	Training Loss: 4.505011 	Validation Loss: 4.340881
Validation loss decreased (4.385202 --> 4.340881).  Saving model ...
Epoch: 6 	Training Loss: 4.445457 	Validation Loss: 4.226356
Validation loss decreased (4.340881 --> 4.226356).  Saving model ...
Epoch: 7 	Training Loss: 4.384697 	Validation Loss: 4.188579
Validation loss decreased (4.226356 --> 4.188579).  Saving model ...
Epoch: 8 	Training Loss: 4.324126 	Validation Loss: 4.178916
Validation loss decreased (4.188579 --> 4.178916).  Saving model ...
Epoch: 9 	Training Loss: 4.291204 	Validation Loss: 4.144304
Validation loss decreased (4.178916 --> 4.144304).  Saving model ...
Epoch: 10 	Training Loss: 4.251021 	Validation Loss: 4.078799
Validation loss decreased (4.144304 --> 4.078799).  Saving model ...
Epoch: 11 	Training Loss: 4.184426 	Validation Loss: 4.082335
Epoch: 12 	Training Loss: 4.132999 	Validation Loss: 3.957970
Validation loss decreased (4.078799 --> 3.957970).  Saving model ...
Epoch: 13 	Training Loss: 4.102434 	Validation Loss: 3.956661
Validation loss decreased (3.957970 --> 3.956661).  Saving model ...
Epoch: 14 	Training Loss: 4.062603 	Validation Loss: 3.876156
Validation loss decreased (3.956661 --> 3.876156).  Saving model ...
Epoch: 15 	Training Loss: 4.002532 	Validation Loss: 3.946470
Epoch: 16 	Training Loss: 3.958243 	Validation Loss: 3.768752
Validation loss decreased (3.876156 --> 3.768752).  Saving model ...
Epoch: 17 	Training Loss: 3.923767 	Validation Loss: 3.801050
Epoch: 18 	Training Loss: 3.865177 	Validation Loss: 3.744687
Validation loss decreased (3.768752 --> 3.744687).  Saving model ...
Epoch: 19 	Training Loss: 3.842686 	Validation Loss: 3.747512
Epoch: 20 	Training Loss: 3.810184 	Validation Loss: 3.804780
Epoch: 21 	Training Loss: 3.776392 	Validation Loss: 3.763188
Epoch: 22 	Training Loss: 3.722326 	Validation Loss: 3.674274
Validation loss decreased (3.744687 --> 3.674274).  Saving model ...
Epoch: 23 	Training Loss: 3.705488 	Validation Loss: 3.694445
Epoch: 24 	Training Loss: 3.674622 	Validation Loss: 3.596416
Validation loss decreased (3.674274 --> 3.596416).  Saving model ...
Epoch: 25 	Training Loss: 3.627540 	Validation Loss: 3.636409

(IMPLEMENTATION) Test the Model

Try out your model on the test dataset of dog images. Use the code cell below to calculate and print the test loss and accuracy. Ensure that your test accuracy is greater than 10%.

In [17]:
def test(loaders, model, criterion, use_cuda):

    # monitor test loss and accuracy
    test_loss = 0.
    correct = 0.
    total = 0.

    model.eval()
    for batch_idx, (data, target) in enumerate(loaders['test']):
        # move to GPU
        if use_cuda:
            data, target = data.cuda(), target.cuda()
        # forward pass: compute predicted outputs by passing inputs to the model
        output = model(data)
        # calculate the loss
        loss = criterion(output, target)
        # update average test loss 
        test_loss = test_loss + ((1 / (batch_idx + 1)) * (loss.data - test_loss))
        # convert output probabilities to predicted class
        pred = output.data.max(1, keepdim=True)[1]
        # compare predictions to true label
        correct += np.sum(np.squeeze(pred.eq(target.data.view_as(pred))).cpu().numpy())
        total += data.size(0)
            
    print('Test Loss: {:.6f}\n'.format(test_loss))

    print('\nTest Accuracy: %2d%% (%2d/%2d)' % (
        100. * correct / total, correct, total))

# call test function    
test(loaders_scratch, model_scratch, criterion_scratch, use_cuda)
Test Loss: 3.665541


Test Accuracy: 14% (125/836)

Step 4: Create a CNN to Classify Dog Breeds (using Transfer Learning)

You will now use transfer learning to create a CNN that can identify dog breed from images. Your CNN must attain at least 60% accuracy on the test set.

(IMPLEMENTATION) Specify Data Loaders for the Dog Dataset

Use the code cell below to write three separate data loaders for the training, validation, and test datasets of dog images (located at dogImages/train, dogImages/valid, and dogImages/test, respectively).

If you like, you are welcome to use the same data loaders from the previous step, when you created a CNN from scratch.

In [18]:
## TODO: Specify data loaders
loaders_transfer = loaders_scratch.copy()

(IMPLEMENTATION) Model Architecture

Use transfer learning to create a CNN to classify dog breed. Use the code cell below, and save your initialized model as the variable model_transfer.

In [19]:
import torchvision.models as models
import torch.nn as nn

## TODO: Specify model architecture 
model_transfer = models.resnet50(pretrained=True)

for param in model_transfer.parameters():
    param.requires_grad = False

model_transfer.fc = nn.Linear(2048, 133, bias=True)

fc_parameters = model_transfer.fc.parameters()

for param in fc_parameters:
    param.requires_grad = True

if use_cuda:
    model_transfer = model_transfer.cuda()

Question 5: Outline the steps you took to get to your final CNN architecture and your reasoning at each step. Describe why you think the architecture is suitable for the current problem.

Answer:

1 ) ResNet Model is is choosed because it has best performance for Image Classification.

2 ) This architecture has excellent Feature detection capabilities. The only thing we have to take care of is reduction of Output classes.

3 ) Final Fully-Connected Layer is added with Fully-Connected Layer with output of 133 (total classes of dog).

4 ) The Transfer Learning helps to reduce the training time and effort to develop the model. We can use pre trained model to train the new model. With this effort of cleansing the data is reduced and we can directly focus on hyper parameter tuning and selecting the improving the model accuracy.

(IMPLEMENTATION) Specify Loss Function and Optimizer

Use the next code cell to specify a loss function and optimizer. Save the chosen loss function as criterion_transfer, and the optimizer as optimizer_transfer below.

In [20]:
criterion_transfer = nn.CrossEntropyLoss()
optimizer_transfer = optim.SGD(model_transfer.fc.parameters(), lr=0.02)

(IMPLEMENTATION) Train and Validate the Model

Train and validate your model in the code cell below. Save the final model parameters at filepath 'model_transfer.pt'.

In [21]:
# train the model
n_epochs = 25
model_transfer = train(n_epochs, loaders_transfer, model_transfer, optimizer_transfer, criterion_transfer, use_cuda, 'model_transfer.pt')
# load the model that got the best validation accuracy (uncomment the line below)
model_transfer.load_state_dict(torch.load('model_transfer.pt'))
Epoch: 1 	Training Loss: 3.629816 	Validation Loss: 1.977586
Validation loss decreased (inf --> 1.977586).  Saving model ...
Epoch: 2 	Training Loss: 2.115053 	Validation Loss: 1.086299
Validation loss decreased (1.977586 --> 1.086299).  Saving model ...
Epoch: 3 	Training Loss: 1.603503 	Validation Loss: 0.837156
Validation loss decreased (1.086299 --> 0.837156).  Saving model ...
Epoch: 4 	Training Loss: 1.375696 	Validation Loss: 0.693085
Validation loss decreased (0.837156 --> 0.693085).  Saving model ...
Epoch: 5 	Training Loss: 1.251421 	Validation Loss: 0.634795
Validation loss decreased (0.693085 --> 0.634795).  Saving model ...
Epoch: 6 	Training Loss: 1.179052 	Validation Loss: 0.563515
Validation loss decreased (0.634795 --> 0.563515).  Saving model ...
Epoch: 7 	Training Loss: 1.115202 	Validation Loss: 0.541549
Validation loss decreased (0.563515 --> 0.541549).  Saving model ...
Epoch: 8 	Training Loss: 1.058895 	Validation Loss: 0.496646
Validation loss decreased (0.541549 --> 0.496646).  Saving model ...
Epoch: 9 	Training Loss: 1.055500 	Validation Loss: 0.468430
Validation loss decreased (0.496646 --> 0.468430).  Saving model ...
Epoch: 10 	Training Loss: 0.990945 	Validation Loss: 0.451072
Validation loss decreased (0.468430 --> 0.451072).  Saving model ...
Epoch: 11 	Training Loss: 0.961948 	Validation Loss: 0.457174
Epoch: 12 	Training Loss: 0.948149 	Validation Loss: 0.426400
Validation loss decreased (0.451072 --> 0.426400).  Saving model ...
Epoch: 13 	Training Loss: 0.903768 	Validation Loss: 0.425230
Validation loss decreased (0.426400 --> 0.425230).  Saving model ...
Epoch: 14 	Training Loss: 0.902779 	Validation Loss: 0.415200
Validation loss decreased (0.425230 --> 0.415200).  Saving model ...
Epoch: 15 	Training Loss: 0.877845 	Validation Loss: 0.417847
Epoch: 16 	Training Loss: 0.880070 	Validation Loss: 0.418715
Epoch: 17 	Training Loss: 0.865671 	Validation Loss: 0.393824
Validation loss decreased (0.415200 --> 0.393824).  Saving model ...
Epoch: 18 	Training Loss: 0.863379 	Validation Loss: 0.389848
Validation loss decreased (0.393824 --> 0.389848).  Saving model ...
Epoch: 19 	Training Loss: 0.834583 	Validation Loss: 0.402707
Epoch: 20 	Training Loss: 0.819011 	Validation Loss: 0.400257
Epoch: 21 	Training Loss: 0.813427 	Validation Loss: 0.374237
Validation loss decreased (0.389848 --> 0.374237).  Saving model ...
Epoch: 22 	Training Loss: 0.819892 	Validation Loss: 0.375065
Epoch: 23 	Training Loss: 0.824735 	Validation Loss: 0.388508
Epoch: 24 	Training Loss: 0.796481 	Validation Loss: 0.374998
Epoch: 25 	Training Loss: 0.779359 	Validation Loss: 0.378841

(IMPLEMENTATION) Test the Model

Try out your model on the test dataset of dog images. Use the code cell below to calculate and print the test loss and accuracy. Ensure that your test accuracy is greater than 60%.

In [56]:
test(loaders_transfer, model_transfer, criterion_transfer, use_cuda)
Test Loss: 0.452576


Test Accuracy: 86% (719/836)

(IMPLEMENTATION) Predict Dog Breed with the Model

Write a function that takes an image path as input and returns the dog breed (Affenpinscher, Afghan hound, etc) that is predicted by your model.

In [120]:
from PIL import Image
import torchvision.transforms as transforms

### TODO: Write a function that takes a path to an image as input
### and returns the dog breed that is predicted by the model.

data_transfer = loaders_transfer.copy()

# list of class names by index, i.e. a name can be accessed like class_names[0]
class_names = [item[4:].replace("_", " ") for item in data_transfer['train'].dataset.classes]

def predict_breed_transfer(img_path):
    global model_transfer
    global transform_pipeline
    # load the image and return the predicted breed

    image = Image.open(img_path).convert('RGB')
    transform_pipeline = transforms.Compose([transforms.Resize(size=(224, 224)),
                                        transforms.ToTensor()])

    # Removing transparent, alpha
    image = transform_pipeline(image)[:3,:,:].unsqueeze(0)
    
    if use_cuda:
        model_transfer = model_transfer.cuda()
        image = image.cuda()
    
    model_transfer.eval()
    idx = torch.argmax(model_transfer(image))
    return class_names[idx]
In [121]:
#Test predict_breed_transfer

for img_file in os.listdir('/data/dog_images/test/001.Affenpinscher'):
    img_path = os.path.join('/data/dog_images/test/001.Affenpinscher', img_file)
    predition = predict_breed_transfer(img_path)
    print("image_file_name: {0}, \t predition breed: {1}".format(img_path, predition))
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00036.jpg, 	 predition breed: Maltese
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00047.jpg, 	 predition breed: Maltese
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00071.jpg, 	 predition breed: Affenpinscher
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00023.jpg, 	 predition breed: Affenpinscher
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00048.jpg, 	 predition breed: Kerry blue terrier
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00058.jpg, 	 predition breed: Lhasa apso
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00078.jpg, 	 predition breed: Giant schnauzer
image_file_name: /data/dog_images/test/001.Affenpinscher/Affenpinscher_00003.jpg, 	 predition breed: Briard

Step 5: Write your Algorithm

Write an algorithm that accepts a file path to an image and first determines whether the image contains a human, dog, or neither. Then,

  • if a dog is detected in the image, return the predicted breed.
  • if a human is detected in the image, return the resembling dog breed.
  • if neither is detected in the image, provide output that indicates an error.

You are welcome to write your own functions for detecting humans and dogs in images, but feel free to use the face_detector and human_detector functions developed above. You are required to use your CNN from Step 4 to predict dog breed.

Some sample output for our algorithm is provided below, but feel free to design your own user experience!

Sample Human Output

(IMPLEMENTATION) Write your Algorithm

In [122]:
### TODO: Write your algorithm.
### Feel free to use as many code cells as needed.
from PIL import Image
def run_app(img_path):
    ## handle cases for a human face, dog, and neither
    if face_detector(img_path) > 0:
        breed = predict_breed_transfer(img_path)
        print('Human / resembing dog breed is ' + breed)
    elif dog_detector(img_path):
        breed = predict_breed_transfer(img_path)
        print('Dog / dog breed is ' + breed)       
    else:
        print('Not Dog, Neither Human')

Step 6: Test Your Algorithm

In this section, you will take your new algorithm for a spin! What kind of dog does the algorithm think that you look like? If you have a dog, does it predict your dog's breed accurately? If you have a cat, does it mistakenly think that your cat is a dog?

(IMPLEMENTATION) Test Your Algorithm on Sample Images!

Test your algorithm at least six images on your computer. Feel free to use any images you like. Use at least two human and two dog images.

Question 6: Is the output better than you expected :) ? Or worse :( ? Provide at least three possible points of improvement for your algorithm.

Answer: (Three possible points for improvement)

1 ) More image datasets of dogs will improve training models. Also, more image augmentations trials (flipping vertically, move left or right, etc.) will improve performance on test data.

2 ) Hyper-parameter tunings: weight initializings, learning rates, drop-outs, batch_sizes, and optimizers will be helpful to improve performances.

3 )Try other models, in particular the Resnet model which is the state-of-the art for imagenet.

4 ) Tune the Transfer Model more - it improved at epoch 25 so it might do better with more training (I stopped because of the time it took to train it).

5 )Try alternatives to Stochastic Gradient Descent - in particular Adam optimization - to improve training.

In [127]:
## TODO: Execute your algorithm from Step 6 on
## at least 6 images on your computer.
## Feel free to use as many code cells as needed.

## suggested code, below
img_path = os.path.join('/home/workspace/dog_project/computerimages','dog1.jpg')
print("image_file_name: {0} ".format(img_path))
run_app(img_path)
Image.open(img_path)
image_file_name: /home/workspace/dog_project/computerimages/dog1.jpg 
Human / resembing dog breed is American eskimo dog
Out[127]:
In [128]:
img_path = os.path.join('/home/workspace/dog_project/computerimages','dog2.jpg')
print("image_file_name: {0} ".format(img_path))
run_app(img_path)
Image.open(img_path)
image_file_name: /home/workspace/dog_project/computerimages/dog2.jpg 
Dog / dog breed is Great pyrenees
Out[128]:
In [129]:
img_path = os.path.join('/home/workspace/dog_project/computerimages','dog3.jpg')
print("image_file_name: {0} ".format(img_path))
run_app(img_path)
Image.open(img_path)
image_file_name: /home/workspace/dog_project/computerimages/dog3.jpg 
Dog / dog breed is Chinese shar-pei
Out[129]:
In [135]:
img_path = os.path.join('/home/workspace/dog_project/computerimages','dog4.jpg')
print("image_file_name: {0} ".format(img_path))
run_app(img_path)
Image.open(img_path)
image_file_name: /home/workspace/dog_project/computerimages/dog4.jpg 
Human / resembing dog breed is Beagle
Out[135]:
In [136]:
img_path = os.path.join('/home/workspace/dog_project/computerimages','dog5.jpg')
print("image_file_name: {0} ".format(img_path))
run_app(img_path)
Image.open(img_path)
image_file_name: /home/workspace/dog_project/computerimages/dog5.jpg 
Not Dog, Neither Human
Out[136]:
In [138]:
img_path = os.path.join('/home/workspace/dog_project/computerimages','dog6.jpg')
print("image_file_name: {0} ".format(img_path))
run_app(img_path)
Image.open(img_path)
image_file_name: /home/workspace/dog_project/computerimages/dog6.jpg 
Human / resembing dog breed is Italian greyhound
Out[138]: